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FURTHER STUDIES ON BLOOD PROTEIN POLY- MORPHISM IN SPRAT

BY

GUNNAR NEVDAL Institute of Marine Research, Bergen

I N T R O D U C T I O N

Polymorphism of hemoglobins and serum transferrins of sprat, Sprattus sprattus (L.), has been described on basis of 28 samples from the Norwegian coast (NWVDAL 1968). Reliability of the type determinations, heredity and choice of characteristic sample parameters were discussed, ancl significant differences, especially among the samples from western Norway, were noted. The purpose of the present study has been to com- pare sprat from the Norwegian coast to the sprat population a t its poten- tial origin areas (see DANNEVIG 195 1 for references).

M A T E R I A L A N D M E T H O D S

Sampling and treatment of hemoglobins and sera, analyses by electro- phoresis, staining of proteins, etc. were performed in the same way as described by N ~ V D A L (1968). Sampling localities are shown in Fig. 1 and listed in Table I together with sampling dates and numbers of specimens determined for hemoglobin and serum transferrill types.

Samples collected a t the same place on the same day were taken from different catches. Numbers in brackets indicate unreliable results due to aging or warming of the samples before the analyses. These results have been omitted in the discussion.

The age of the sprat was determined partly from size ancl partly from growth zones in the otoliths.

R E S U L T S A N D D I S C U S S I O N

Distributions of hemoglobin types in the 1967 and 1968 samples are shown in Table 1 (Norwegian coast) and Table 2 (North Sea and Kattegat). The type HbI-1-3 was not found in these samples. Correspond- ing distributions of transferrill types are shown in Table 3 and Table 4.

The distributions and the diagram of the 95 per cent limits of confidence (Fig. 2) show good agreement between the results from the samples

Fig. 1. Sampling localities of blood samples of sprat in 1967 and 1968.

Table 1. Distribution of hemoglobin patterns (phenotypes) in samples of sprat from the Norwegian coast 1967 and 1968.

collected in 1967 and 1968 from the Norwegian coast and the results from previous years. Great variations were observed among samples, especially among samples from western Norway.

High value of HbI-1 frequencies and intermediate values of q, characterized the samples from Kattegat. Fig. 2 shows that part of the samples from western Norway, most of the samples from the Skagerak coast and one sample from the Oslo fjord coincided with the Kattegat samples. Most of the samples from the North Sea also showed high zralue of HbI-1 frequencies while some had higher q, values than the Kattegat samples. These results were also in accordance with the results of a few of the samples collected at the Norwegian coast. However, a considerable part of the samples collected at the coast had conformity neither with the samples from Kattegat nor with the samples from the North Sea. This is illustrated in Fig. 3 where both the q,-values and the HbI-1 frequencies for each sample are plotted in a scattering diagram. Samples with less than 50 reliable determinations of specimens have been omitted, but the previous samples (NEVDAL 1968) are included.

The most likely explanation of the variation among samples is that the samples are collected from populations which differ in their gene pool,

Hemoglobin patterns Frequency

Sample

of pattern no.

1

1

1 1

2 9 30 3 1 32 3 3 34 35 36 37 38 39 40 41 42 43 44 45 47 48 49

82 24 1 2 3 110 74.5

92 8 ^{- - -} 100 92.0

8 1 6 - ^- 1 88 92.5

96 8 ^{- -} 104 92.3

105 14 - ^- 4 123 85.4

92 10 ^- 1 2 105 87.6

75 19 2 ^- 1 97 77.3

79 22 ^{- -} 3 104 76.0

74 24 4 1 1 104 71.2

66 11 - 1 ^- 78 84.6

70 9 ^- 1 ^- 80 87.5

58 4 - - - 62 93.5

83 9 ^{- -} 1 93 89.2

64 18 1 2 6 91 70.3

34 13 - - 3 50 68.0

43 10 ^{- -} 2 55 78.2

69 8 - ^- 1 78 87.2

93 2 ^- - ^- _{95 97.9}

118 2 - - - 120 98.3

113 5 - - - 118 95.8

Y.

0.10

40 41 38 39 34 35 29 33 42 36 37 31 30 32 48 49 45 43 47 46 44 54 50 52 51 53 57 55 56 S A M P L E NO ---+

TR.HEIMS NORDFJORD SOGN AND SUNNHORDLAND SKAGERAK OSLO FJORD NORTH SEA KATTEGAT

FJORD NORDHORDLAND COAST

Fig. 2. Confidence intervals for the universal frequencies of HbI-1 and for the gene

Tf supposed to control the transferrins in the Tf A-group. Horizontal lines mark the observed frequencies, and the vertical bars show the 95% confidence limits. The samples

are arranged in geographical order.

7 0 75 8 0 8 5 9 0 95

FREQUENCY OF H B 1-1

.WESTERN NORWAY + SOUTEASTERN NORWAY O NORTH SEA DKATTEGAT

Fig. 3. Relation between frequencies of the helnoglobin type HbI-1 and the transferrin gene Tf A in sprat samples. Samples of less than 50 specimens are omitted in the

diagram.

Table 2. Distributions of hemoglobin pattern in samples of sprat froill the North Sea and Kattcgat.

- -

that is populations which are reproductively separated. T h e results therefore indicate that a major part of t l ~ e sprat in Norwegian waters may be recruited from spawning grounds in the Kattegat. Recruitement from the North Sea may also account for a part of the Norwegian sprat population. The origin of the sprat from which the rest of the samples have been taken, is not clear, but local populations in the fjords may be one explanation. I t is also possible that the samples from Kattegat and the N o r t l ~ Sea are not representative for these areas, and t l ~ a t other sprat populations exlst from which no samples have been taken.

I t is evident that no covariance exists between the observed pair of values (Fig. 3). This implies that more than two separated populations have been sampled, although some of the samples may represent a mixture of specimens of different origin. The mechanism wliicl~ prevents gene flow between the populations, is still unknown.

T h e results of the studies on blood proteins of sprat indicate the following conclusion: the sprat population in Norwegian coastal waters consists of a major group recruited from spawning grounds in the Kattegat and the North Sea and minor groups recruited from local populations in the fjords.

I-Icmoglobin patterns Frequency

Saillplc

of pattern no.

1

¹

1

S U M M A R Y

1. About 3000 specimens comprising 29 samples of sprat have been analysed for hemoglobin and serum protein types. The samples were collected at different localities on the Norwegian coast, in Kattegat and the North Sea.

2. The results of the samples from the coast confirm the results obtained by corresponding studies macle before, i.e. great variations among samples, especially among s a m ~ l e s from western Norway.

5 1 52 53 54 55 56 5 7

5 1 8 ^{- -} 1 60 85.0

106 5 ^{- - -} 111 95.5

7 7 3 ^- 2 82 93.9

109 3 ^{- - -} 112 97.3

74 1 - - 75 98.7

112 2 - - - 114 98.2

307 12 - ^- 2 32 1 95.6

Table 3. Observed distributions of transferrin groups in samples of sprat from the hTorwegian coast compared to expected Hardy-Weinberg distributions.

Sample Transferrin groups

Probability of worse fit I

29 o'cs 15 exp 18.0 30 obs 16

cxp 13.4 31 oEs 9

e xP 9.2 32 obs 11

exP 9.6 33 GFS 17

exp 16.1 34 oEs 11

cxp 11.0 35 obs 11

exp 10.4 36 oEs 11

exp 12.5

37 obs 7

exP 8.3 38 obs 5

c xl' 5.5 39 obs 9

exP 9.2 40 oks 4

exP 5.8

41 obs 10 exp 11.8 4 2 o b s 14

exp 10.6 43 obs 16

exp 13.8

44 obs 7

exP 7.3 45 obs 8

exP 7.6 46 obs 8

exp 10.2 47 obs 9

exP 7.9 48 obs 12

exp 11.3 49 obs 11

exp 12.7

Table 4. Observed distributions of transferrin groups in samples of sprat from the North Sea and Kattegat compared to expected Hardy-Weinberg distributions

Trasferrin groups

Sample Probability of

worse fit I

50 obs exp 51 obs exP 52 obs e XP 54 obs

exp 55 obs exP 56 obs exP 57 obs exP

3. The Icattegat samples coincided with part of the samples from western Norway, with most of the samples from the Skagerak coast and with one sample from the Oslo fjord. The samples from the North Sea also showed accordance with some of the samples from the Norwegian coast.

4. The present and previo~ts analyses indicate that the sprat population in Norwegian waters consists of one major component recruited from Kattegat and the North Sea, and minor components recruited from local spawning in the fjords.

A C K N O W L E D G E M E N T

I want to express my gratitude to several fishermen, to the staff of NEPTUN CANNING CO., A/S BERGENHUS CANNING CO. and NOREGS SILDE-

SALGSLAG for help in obtaining samples. Likewise my thanks are due to director G. DANNEVIG, Statelis Biologiske Stasjoil Fladevigen, Arendal, for valuable discussioll and encouragement and to the technical assistents who have carried out the analyses.

REFERENCES

DANNEVIG, G. 1951. Sprat from Norwegian waters. An analysis of vertebrae counts.

FiskDir. Skr. Ser. HnuUnclers., 9(12) : 1-22.

NAEVDAL, G. 1968. Studies on hemoglobins and serum proteins in sprat from Norweg.ian waters. FirkDir. Skr. Ser. HavUnclenr., 14: 160- 182.

Received 4 December 1968 Printed 1 April 1970

Table I. Number of specimens analysed for hemoglobin and transferrin types in blood samples of sprat from western Norway (29-42), southeastern Norway (43-49),

North Sea (50-54) and Kattegat (55-57).

Sample _no. Locality

/

(

/

/

Risnes, Masfj Hordaland

Skorpo, Hardangerfj, Hordaland

Gjermundshamn, Hordaland

Skorpo, Hardangerfj, Hordaland

Duesund, Masfj, Hordaland Haveland, Sogn Oppedalsmyra, Sogn Lygrespollen, Hordaland Lygrespollen, Hordaland Tistam, Nordfjord Tistam, Nordfjord Borgenfjorden, Trmndelag Innvik, Nordfjord Asgard, Austfj, Hordaland Bolazrne, Oslofjorden Vollen, Oslofjorden Sandnesfj, Aus t-Agder Bastoy Oslofjorden Husvik, Tonsberg Oslofjordell Flodevigen Aust-Agder Flodevigen Aust-Agder 56"101N, 05"25'E North Sea 55"00'N, 06"00'E North Sea 55"08'N, 03"32'E North Sea

4 June 6 7 6 June 67 6 June 67 6 June 67 12 June 67 19 June 67 19 June 67 26 June 67 26 June 67

1 $2-group 1

+

group 1 -group 0-group 14 Oct. 67

14 Oct. 67 26 Oct. 67 26 June 68

12 Oct. 68 9 Sept. 68 13 Sept. 68 29 Sept. 65

30 Aug. 68 23 Oct. 68 25 Oct. 68 24 Aug. 67

29 Aug. 67

Table I (cont.) Sample

no.

53 54 55 56 57

Locality

/

/

/

53"19'N, 0Z045'E 16 Sept. 67 82 - 2-group North Sea

58"21'N, 00°45'E 20 Sept. 67 112 30 2-group North Sea

57"35'N, 10°55'E 8 Nov. 67 75 63 2-group Kattegat

57"35'N, 10°55'E 8 Nov. 67 114 95 1 -group 57"43'N, 10°50'E 10 Nov. 67 321 322 2-group K a t t e ~ a t